RESUMO
PURPOSE: This study was performed to create a traumatic brain injury (TBI) animal model of up-regulated bone formation, and to show the possibility of comprehensive analysis of early gene expression from the hard tissue by cDNA microarray technique. MATERIALS AND METHODS: Thirty Sprague-Dawley rats underwent either a severe brain injury operation procedure using the water pump with femur fracture (Group I, N=15), or femur frecture only (group II, N=15). The femur was nailed with a 20-gauge needle and fractured. The rats were euthanized at the day 1, 3, 8, 14, and 28 day. The volume of callus was calculated using GE PACS(R). The total RNA was isolated from the 3rd day's callus and the gene expression was compared using microarray chips. RESULTS: The average time until union was 28 days for control group and 14 days for TBI group, which was significantly shorter. The volume of the callus (27.4+/-8.5 mm2) in the TBI animals was clearly greater than that of the control group (13.0+/-6.3 mm2). The mRNA was successfully extracted from the callus and analysed using the c-DNA microarray, and. 312 genes were significantly increased and 227 genes were decreased in the TBI group. CONCLUSION: This study successfully made a model for a accelerated fracture healing in traumatic brain injury. We showed that cDNA microarray technique can be used to compare the expression of the mRNA in fracture callus. This method will be helpful in analysing the mechanism of accelerated fracture healing after brain injury.